Ultrasonic-assisted alkali leaching coupled gas sorting process to separate cathode and anode materials from spent LiFePO4 batteries

Abstract

With the rapid development of lithium-ion batteries, the recycling of spent batteries represents a major future challenge, particularly LiFePO₄ batteries (LFP) due to their structural stability and high safety. This study proposes a simple and efficient pretreatment process, employing a combination of ultrasonic-assisted dilute alkali leaching and crushing-gas sorting to separate the cathode and anode material from spent LFP, respectively. The key parameters that affect the recovery efficiency of cathode materials from Al foil have been determined, including alkali concentration, liquid-solid ratio, ultrasonic frequency, and ultrasonic time. The separation efficiency between Al foil and cathode material can achieved 99.85 %. The interface effect generated by the ultrasound cavitation promotes the separations of Al foil and cathode active materials. Meanwhile, the optimal crushing-gas sorting process parameters including particle size and gas flow rate was determined to recover Cu foil and graphite from the anode active material. A Cu recovery efficiency of 87.2 % with a Cu grade of 84.6 % was reached. Additionally, treatment with 3 % HCl for 90 min was introduced to remove the residual Li in the recovered graphite. This method can provide a more efficient and sustainable way for the comprehensive separation and recovery of active materials from spent lithium-ion batteries.